Around 65% of ScotRail's fleet is old enough to require replacement within the next few years, forcing Transport Scotland and Scottish Rail Holdings to plan a consolidation from today's 11 fleets to roughly five main groups in what officials describe as a once-in-a-generation opportunity to reshape the network.

The strategy, outlined by Bill Reeve and Louise Shaw of Transport Scotland and Jon Newton of Scottish Rail Holdings at an IMechE event in May 2026, treats fleet replacement as a whole-system programme rather than a series of rolling stock orders. Electrification, depot capacity, station platforms, and digital systems including passenger information and onboard connectivity must all move in step with new trains.

Scotland's collaborative model — ScotRail and Caledonian Sleeper under Scottish Rail Holdings working with Network Rail, all funded and specified by Transport Scotland — has already delivered measurable results. Electrification costs around 30% less per single track kilometre than in England, and signalling work is being delivered more efficiently too.

Much of the current fleet is both old and unusually varied, driving up maintenance complexity, training costs, and spares difficulty. Many trains have already had their lives extended and now suffer corrosion, wiring deterioration, and parts obsolescence. Fleet renewal is also intended to serve wider Scottish Government transport goals on equality, climate action, economic growth, and health.

Demand shift drives design requirements

Since 2020, weekend and leisure travel have strengthened while Monday and Friday commuting has weakened. In 2025, ScotRail's busiest days coincided with major sports events, concerts, the Edinburgh Festivals, and the weekend before Christmas. Scotland also forecasts a demographic shift towards an older population, increasing demand for step-free access and better spaces for luggage, buggies, and wheelchairs, while a smaller working-age population may make maintenance and operations recruitment harder.

Inter-City: HSTs out, Class 222s in from 2027

The urgent priority is replacing the High Speed Trains, now around 50 years old, increasingly expensive to maintain, and delivering poor availability. Inter-City services account for a relatively small share of ScotRail's mileage but generate significant revenue and anchor business and tourism traffic.

The immediate answer is 22 five-car Class 222 trains cascaded from East Midlands Railway. Leased from Beacon until 2036, with an option to extend into the early 2040s, they will undergo heavy maintenance and extensive refurbishment by Alstom and are expected to enter service from 2027.

The refurbishment includes a ScotRail livery repaint, interior refresh, a multimedia passenger information system, WiFi using Low Earth Orbit satellite connectivity with voice-over-internet capability, a new electronic seat reservation system, new CCTV, and an intelligent engine start-stop system to cut emissions. New First and Standard Class seats will offer 240 V plug sockets plus USB-A and USB-C at every seat. The trains will also feature a family-friendly area, one wheelchair space in First Class and two in Standard, storage for six bikes, onboard catering facilities, and seat layouts optimised for window alignment and luggage.

Although diesel powered, the Class 222s are expected to be more fuel efficient than the HSTs. The lease runs until enough electrification is completed to enable battery-electric Inter-City multiple units; the routes to Aberdeen and Inverness will need partial electrification by 2040 for battery-electric operation to work.

Suburban fleet: minimum of 69 new trains in procurement

The largest day-to-day impact will come from the suburban fleet procurement, already under way, because these services carry the biggest share of ScotRail passengers. Most of the existing suburban fleet is approaching or has passed 40 years old. Official notices specify a minimum of 69 trains, with options for up to approximately 37 more.

The plan is for a standardised fleet of battery-electric multiple units (BEMUs) to replace Class 156 diesel units, and EMUs to replace Classes 318 and 320, with an option to replace Class 334 — only 25 years old now, but 30-35 by the time of replacement. Requirements include air-conditioning, greater reliability, level-access boarding designed to minimise platform adjustments, improved cycle and wheelchair provision, and family-friendly areas.

BEMU deployment brings system-level challenges: timetable and diagram design must create battery-charging opportunities; topography, speeds, and battery size determine self-powered range; power supply capacity must support full operation through electrified sections; and depots and stabling points may need higher-capacity supplies for charging. Transport Scotland points to the Cardiff Valley lines discontinuous electrification modelling as the template for this iterative design process. Intermittent electrification will be provided on the Fife and Borders lines to enable BEMU operation, with the displaced diesel units cascaded to rural routes to improve services on the West Highland and southwest Scotland lines.

Rural routes deferred

Rural and scenic routes, which support tourism, connect communities, and link to ferry services, will see cascaded Class 158s and 170s in the shorter term. Permanent traction and infrastructure decisions remain open and will follow later choices on electrification.

Sequencing and economics

A full procurement cycle from business case to fleet introduction can stretch over a decade, and planners say work must start around 10 years before trains are required. The supply chain cannot deliver multiple large fleets simultaneously without risk, and depots are already busy with finite stabling space.

The economics present a political challenge. Old trains carry low lease costs but rising and sometimes unexpected maintenance bills, while new trains cost more to lease but are cheaper to run. The crossover point where new builds become cheaper may lie years away, while funding decisions must be made now.

With electrification as the preferred end-state for most of the network — battery trains serving a transitional role on partly electrified routes — the programme's phasing will determine whether Scotland converts its ageing fleet problem into a simpler, cleaner, and more reliable railway, or repeats the stop-start investment pattern it has so far avoided.